This application relates to a novel optical fiber laser delivery system and the method of using the same. Such delivery systems are now used for certain types of surgery, such as arthroscopic surgery.
Laser radiation is used in surgical applications where the cutting of tissue is desired, or where the target tissue, such as a tumor, is to be destroyed. In such systems, various types of laser radiation have been used i.e. both continuous wavelength and pulsed, the radiation being passed through an optical fiber, and to the fiber tip. To achieve better cutting efficiency, the fiber tip is placed immediately adjacent the tissue target.
We have found that high energy pulsed laser radiation provides an effective means for such tissue destruction. For example, we have found that very effective delivery of radiation occurs where energies of two joules over a pulse of 350 microseconds are delivered at a frequency of ten hertz.
While the use of high energy pulsed radiation is effective for the destruction of tissue, we have found that catastrophic damage to the tip of the optical fiber carrying such radiation likewise occurs in many cases. Clearly, such damage is costly from a reliability standpoint. More importantly, failure of the fiber tip during surgery could lead to the deposit of debris from the destroyed tip in the patient's body.
It is theorized that fiber tip breakdown results from at least three mechanisms. First, there may be inherent structural weaknesses arising from manufacture, such as microcracks and polishing or cleaving defects. Second, exposure of even structurally sound fiber tips to the explosive forces and acoustic shock waves generated at the tip when high energy pulsed radiation is used can cause damage to the fiber. Third, thermal shock may occur.
Thus, it would be advantageous to provide a contact optical fiber laser delivery system for surgery wherein the delivery system was designed to minimize damage to the fiber tip arising from exposure to the forces generated when the fiber is used to transmit high energy laser radiation to the surface of the tissue in question.